A COMPACT DISC-RECORDABLE COMPATIBLE DIGITAL VERSATILE DISC PICKUP WITH A LENS FOR 780 NM AND 650 NM WAVELENGTHS

Two types of compact disc-recordable(CD-R) compatible digital versatile disc (DVD) pickups have been developed. One has separate conjugate points for DVD and compact disc(CD) readouts. The other has a common conjugate point for DVD and CD readouts. Optical and signal properties are considered for both types. Both types have been shown to exhibit good qualities for practical use.